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We have been living in the house for almost a year now, how time flies. The Genvex Combi 185LS has performed really well, providing hot water and supplementary space heating. The MVHR system is part of Genvex Combi 185LS. One advantage of the Genvex ventilation system is that having an EASHP built in means that the supply air temperature is always slightly above room temperature even if it is not in heating mode. A standard MVHR unit would deliver air at a few degrees below room temperature, hence feeling cool, unless a post heater were fitted.
I recently realised I had forgotten to write up the process we went through when setting up the ventilation. When we commissioned the ventilation system we set it up for the building regulations rates which were quite high. After the house had been signed off we changed the air flow rates to Passivhaus levels. The Genvex has four ventilation levels and the speed of the supply and extract fans can be altered for each level making it relatively easy to balance the system.
To set the flow rates I used a Testo 405i anemometer fitted into a piece of flared ducting held over the supply or extract valve. The Testo 405i has a bluetooth link to a portable device running an app which stores and outputs the results. This makes the process much easier than having to write down results each time.
I created a table of room volumes along with Passivhaus air change rates and from that calculated the flow rate and hence flow velocity.
I then adjusted each of the room valves for the extract side starting with the room closest to the Genvex unit and then the next room further away until all the rooms were finished. This process was then repeated along with adjusting the fan speed until the required flow velocities were correctly set up for each room. This was then carried out for the supply side. We found that the set up procedure was very sensitive to wind speed, so we carried out the commissioning on a calm day.

We had lived in the 1920s timber framed bungalow for the last ten years, which although small, allowed us to live comfortably enough while doing the self build. After we moved into the new house we had three months to demolish the bungalow, which was a planning condition. We found out that the bungalow was stick built in the 1920s for farm workers as a Home for Heroes after the First World War. The main part consisted of four rooms and was constructed from 4"x2" timber, lined with Chrysotile asbestos boards and the outside clad with feather edge timber. It was built on a small concrete ring beam. In the 1950s the outside cladding was obviously deteriorating so was battened out and expanded metal mesh was added which was then rendered in pebbledash. At the same time a brick built extension housing a bathroom was added at the rear. In the 1980s a porch was added along with a full width rear extension housing a kitchen and bathroom. An oil fired central heating system was also added.
We decided to dismantle the bungalow rather than knock it down as the site is small and the bungalow was less than 0.5m from the new house. This meant dismantling the bungalow in 'layers' and disposing of the materials before moving onto the next part. We took out the carpets, wiring and plumbing and disposed of that. We put all the doors and secondary glazing on Freegle and they were soon taken. While we were waiting for quotes for the asbestos removal we took off the pebbledash.
We only realised how poor the state of the bungalow was when we started to dismantle it. The sole plate had rotted completely in places as had the bottom of some of the studs.
We then had the internal asbestos boards removed and at the same time I took the asbestos slates off the roof. I was doing that when we had a very hot spell and the glue melted on the soles of a pair of my trainers and working boots, so they went in the bin. I was glad when that job was finished as were the asbestos removers inside the bungalow. Once the asbestos was gone we took off the sarking boards and feather edge cladding. The sarking boards were in quite good condition and went quickly on Freegle but the feather edge was shot so we cut it up and took it to the local tip.
The rafters on the main part of the bungalow were 4"x2" and long and straight and went on Freegle for making chicken runs and animal houses.
The rafters on the extension were 6"x2" and went to make a pergola. The main frame and studwork was taken by a couple of people for different things.
The flooring went to someone with an old basement who wanted old timber flooring. The chimney breast and plinth wall yielded nearly 1600 bricks which someone took for a garden wall. We got homemade jam and some eggs in return.
The last things to go were several hundred concrete blocks so now we just have a pile of mixed rubble left.
We are wondering whether to crush it on site and use it for the driveway and shed base or have it taken away and buy in some type 1.
We're pleased to have been able to dispose of most of the bungalow in a useful way by recycling the materials. It has also helped us by not having to pay for any of the demolition with the exception of the asbestos removal. It has been interesting stripping back the layers and seeing how it was constructed and altered over the years.

We'll be moving in when the heating oil for the bungalow runs out. There's quite a few finishing off jobs to do upstairs so we'll try to get as much done as we can before we move in. We would like the ensuite ready so that's the first on the list.
It's just a job of fitting the basin towel rail and the shower door. Then sealing the basin, toilet and shower.
Next is the bathroom where there are similar jobs to complete.
We decided when we started the build in 2010 that we would like bamboo flooring upstairs as it was hard wearing, looked good and was a good price. Unfortunately when taking a long time to build, prices can go up quite a bit which is what happened with the bamboo flooring, increasing around 30%. It's still worth it though.
We had to remove the landing banisters to fit the first piece of flooring which was the nosing on the edge of the stairwell.
We fitted oak Mexicano doors upstairs which we finished with Osmo Polyx Oil in clear satin. I made the door linings from softwood and painted them white. All the hardware came from IronmongeryDirect.
There are two loft/storage areas which we wanted to complete before moving in. One in the main bedroom over the utility room/wet room and the other over the other two bedrooms and accessed from the landing.
We managed to complete the painting and the flooring, which was bamboo in the lower loft and carpet tiles in the upper loft. This was when the heating oil ran out so we moved in with still the loft doors to make and fit and a bedroom and the bathroom door to fit. Not so bad. Once we had settled in we had to start dismantling the bungalow as there was a time limit on it's removal in the planning conditions. The remaining jobs will be finished over the winter when we can't work outside.

During 2017 we carried out some works in the garden so we wouldn’t be hit with a long list of jobs when the house is finished. The first job was to replace the fence between our property and the neighbours. It was falling down and for two winters I had nailed battens across the posts to stop the panels being blown down. It was put up in the 1980s so had done well.
What we discovered was that the posts had been put in holes around 700mm deep with concrete around the post at the bottom. At a later date the posts had rotted at ground level and angle iron had been screwed to the post and a lot more concrete poured around the angle iron. The posts took a lot of digging out which was made worse by the fact that our oil tank had been installed right next to the fence.
Fortunately there was no one living next door and the neighbour was happy for me to work from his garden. It was very overgrown, so I cleared a metre wide strip to allow me to put up the new fence. I managed to move the oil tank about 0.8m which made it an easier job.
It was painted with Creoseal when finished.
Our planning application showed the garden area with hard landscaping and planting plan. So we dug out the areas for paving and laid 100mm compacted type1 sub-base. This was for a patio area at the rear of the house connected to the area under the side verandah. There is a separate paved pathway from the driveway to the front door which slopes up to the front door to meet building regulations.
The paving is Indian sandstone, which is calibrated, square cut and honed, it is a mixture of pinks, greys, creams and browns. We bought two pallets in a sale and had just enough to do the areas we wanted done with three slabs left over.
It's interesting to see how the colours are brought out when the slabs are wet.
Another job we did was to replace the temporary edging for the grassed area with galvanised steel edging. When we had the front of the driveway laid, the edging used was ExcelEdge AluExcel 150mm. This was very expensive and so for the rear of the driveway and for the front grassed area and side border we used EverEdge Halestem.
We planted a Star jasmine and a couple of planters with lavenders.
We also dug over and graded the soil and laid turf at the front of the house.

The next rooms to be completed were the utility room and the wet room. The utility room houses the electricity supply point, TV aerial splitter, the plumbing system and ventilation point. It is also the location of the Genvex Combi 185 LS which provides the DHW, warm air space heating and the MHRV system. The washing machine or maybe washer/dryer will also be squeezed into the small space. The overall size of the house isn’t large so care was taken to use space efficient components such as the Genvex Combi 185 LS. The Genvex Combi 185 LS is a heavy unit at 210kg but once in position it is easy to connect up. There was an initial problem with the unit in that the anode leaked on installation but that was resolved by removing and refitting. Following the installation instructions, it ran as expected. It is necessary to balance the ventilation system which will be done in the near future, but it seems to be running well. The Optima 312 control unit can be tweaked to set up the unit as you want it.
Warm air heating is the best form of heating in a very low energy house because although air can only carry a small amount of heat, that is all that is required in a house of this type. It is also much more controllable compared to a water based heating system which carries more heat and is therefore subject to slower heating up and cooling down. Bath/shower rooms have electric towel rails so are kept warmer which adds to the heat extracted by the MHRV system.
We still have to finish the cupboards for the electricity meter etc and for the water softener, manifolds and waste pipes. We have a twin cylinder, block salt water softener because the water is quite hard at 320ppm (mg/l). The hardness does vary a little throughout the year depending on the proportion of surface water to aquifer water in the supply.
All the plumbing was carried out using Speedfit plastic push fit pipe and fittings. I’ve found this to be the best of the many types available as it allows collet clips to be fitted indicating that the pipe has been fitted correctly. Speedfit fittings can also be demounted without having to use a special tool. The three bath/shower rooms, kitchen and utility room are all located in one quadrant of the house. This is to reduce the lengths of water pipes that run from the manifolds to the various types of outlet.
The wet room door is an oak Mexicano 35mm thick door. I'm glad I didn't choose the 40mm type as this one was heavy enough for me to hang.
The back/side door is an Internorm PH door.
I drew up the circuit design myself and had it checked by the electrician. I then carried out the first fix and had that checked and tested. When I had finished the second fix the electrician carried out the tests and issued the Part P certificate.
When wiring the lighting circuits I have used the loop at switch method which works well with the Schneider Lisse light switches which have a built in connector for all the neutrals.
The wet room is located next to the utility room so if there were a significant water leak hopefully most of the water would find its way down the wet room drain. When originally designing the house, the wet room was a ground floor cloakroom but the room was increased in size to allow a shower area to be fitted. This fits in with the idea of future proofing to allow single level living if required.

We wanted a modern design staircase that looked as though it were free standing but at a reasonable price. After a lot of searching we found an Italian company called Fontanot. They produce spiral and winder staircases from steel and wood. We visited their distributers at Rotherham and chose the Genius 030 winder staircase with white power coated steel work and natural beech treads. We tweaked the design a little and then placed the order. We were given a four week lead time but it was delivered in three weeks. The whole staircase came in a 1.2m x 1.0m x 0.6m crate. Then it was a case of putting together the biggest kit I've built. There was a DVD with the instructions which was helpful but gave the impression that it could be built quickly, which it most certainly wasn't in our case.
The parts of the spine.
The rest of the kit minus the treads.
To build the staircase you start at the top.
First tread is screwed to the side of the stairwell.
Then you work your way down.
The base of the spine is bolted to the floor.
On the landing the balusters are fitted into cups that are screwed and bolted to the floor.
Finally finished and the treads were covered with a protective film.

I have decided to complete the house by finishing it room by room. The first room was the kitchen, ready for the kitchen units and appliances delivery. We chose a white gloss handleless design supplied by Wrens. We were not impressed by the accuracy of their design when we had to replace a 250mm wide base cupboard with a 350mm cupboard. The units themselves though were well made.
I made a plywood template for the Schock Solido sinks to allow alignment of wastes and tap.
I fitted two floating oak shelves.
The dining area, full of boxes and end panels.
We had a black granite worktop and upstand fitted by a local supplier
We have used AEG appliances with the exception of the
dishwasher and washing machine which are Miele.
The Schock Solido sinks were fitted using G clips.
Behind the induction hob I fitted a black glass splashback which was supplied by a local glass company.

Before I started decorating I wanted to have a preliminary air tightness test. I wasn't sure what sort of value I would achieve because I didn't use an air tightness membrane. I relied on the characteristics of the Icynene foam insulation and on careful use of Soudal Flexifoam along with Compiband tape around the doors and windows. I was hoping for a value of no more than one air change per hour. The technician did a pressurisation and depressurisation test. The pressurisation result was 0.45 ACH and the technician thought he had made an error so did the test again with the same result. Then the depressurisation result was 0.49 ACH. The reason the depressurisation result is slightly higher is because the windows open inwards. So the average result was 0.47 ACH. The test did show up a slight leak around one seal on one window, which has now been adjusted so the final result may be even lower.
The ground floor is fully tiled. The wet room has 305mm square black slate effect porcelain tiles. The rest of the ground floor is tiled with 708mm x 472mm travertine effect porcelain tiles. Both types of tile have a low sheen surface. We used BAL adhesive and grout. The tiler was the same person who did the plastering and the quality of the work was excellent. There were problems with my tile cutter and he wasn't able to tile the whole ground floor so I said I would finish it as he had another job to go to. It left the utility room, wet room and the areas around the pocket doors for me to finish.
Travertine effect tiles
Kitchen/diner
Hall
Sitting room
Utility and wet rooms Utility room tiled Wet room with the easy flat tiling done. Now for the sloping tiles to the drain.
The walls and ceilings are painted with matt white BS00E55 emulsion with the woodwork being coated with eggshell paint of the same colour. We were very lucky and the plasterwork needed virtually no preparation. We used Wickes Plaster Sealer which was excellent, sealing hairline cracks and providing a good surface for the emulsion. All the paint is Albany supplied by Brewers.
The bathroom and ensuite on the first floor have Amtico Spacia tiles. It took some time to find a tile that matched the porcelain tiles in the wet room.

It's coming up to six years now and the front garden still looks like a tip. We're going to put some effort into tidying up and laying out a front garden while the weather remains good.

We put a fence up on the two sides bordering the orchard.

The water table varies from road level down to 2.5m below road level. The Highways Department allowed us to discharge roof drainage directly onto the road because of this. The house damp proof course is 700mm above road level. The road slopes gently down to a ditch 300m down the road which then discharges into a stream. Fortunately the road doesn't flood because of the slope.

We wanted to replace the old soil pipes which had been used as temporary gutter downpipes so we finally fitted all the downpipes around the house and connected then up to the new drainage pipework.

The front garden had been just a place for the crane and lorries to park and offload supplies.

We contracted a company to lay roadside kerbs and form a bellmouth driveway entrance. The remainder of the driveway will be laid where the existing bungalow is after it is demolished.

We barrowed several tons of soil, from the pile in the back garden, to create an even slope from the front of the house to the top of the kerbs.

We put in gate posts before the final resin bound gravel surface was laid on the driveway entrance.

We put a rabbit proof fence along the front and planted a hedge and some heathers and acconites to finish it off.

We finally laid 20mm shingle to finish off around the edge of the house. Only three weeks to Christmas and after the New Year it will be back inside the house tiling the floor.

We used a plasterer who was recommended to us. It was a very good choice as the plaster was flat and as smooth as glass. We found out he was also a qualified venetian plasterer. This was something we hadn't heard of before. He gave us samples, which we liked, and he venetian plastered the bathrooms.

He took a great deal of care and time ensuring the beads were perfect around the hipped dormers.
He masked well around all the windows and doors.
The plasterwork was as good even in the loft areas where it was very cramped.
In the ensuite I built a framework around the hidden cistern and the frames for the wall hung toilet and basin.
It was boarded in using 12mm Hardiebacker board.
It was then venetian plastered.
We did the same in the bathroom.
The shower cubicle in the ensuite was treated in the same way.
As was the downstairs wetroom.

All the walls and ceilings were plasterboarded with 12.5mm square edge, standard (grey) or water resistant (green) plasterboard. The exception were the walls in the wetroom which were boarded with 12mm Hardiebacker board.

The window boards and reveal plasterboarding were completely sealed using Soudal Flexifoam.

The dryliners did an excellent job.
There are three hipped dormers and vaulted ceilings on the first floor which makes boarding a tricky job.
The ensuite and bathroom.
The sitting room has a standard height ceiling for half the length and a vaulted ceiling for the other half. Just to complicate matters.

The depth of the timber I-beams is 350mm which is the thickness of the Icynene. We chose Icynene for its thermal and airtightness qualities. We thought having it sprayed on would be relatively straightforward and quick. We hadn't realised the amount of trimming and tidying that would be needed.

All the openings were masked with clear plastic sheeting.

The front entrance doors and frames were heavily protected to prevent damage from the installation hose. This consisted of three hoses in one. Two for each of the foam chemicals and one for the hot water which kept the chemicals at the correct temperature.

The hose is long enough to reach from the front garden to all the interior walls.

Downstairs ceiling void before spraying.

The thickness was much greater than the installers had carried out before. It proved difficult to achieve the 10mm excess and in practice there was around 50mm excess on average.

The excess was trimmed off by me using a special saw loaned to me by the installers.

Although it took a long time and was messy the finished job was good.

We disposed of around 70 bags of trimmings in all.

The final job was cleaning the faces of the I-beams before plasterboarding. My partner is smaller than me and could reach the parts I couldn't.

Now back inside the house, it’s time for 1st fix. That's ventilation, electrics, plumbing and waste.
I used 125mm diameter rigid plastic pipe for the MHRV ducting.This was the largest diameter that would fit through the metal web joists. It is also compatible with the Genvex Combi 185 compact unit flow requirement.
The supply air passes through an attenuator

The ducting is boxed in and insulated where it leaves the compact unit and goes to the external vent.

Supply vents to the bedroom are at low level coming up through the ceiling.
The water supply pipes are connected using a manifold system. There are separate manifolds for hot water, softened cold water and mains cold water. Each tap or cistern has it's own supply and the pipes run through conduit and have no joins. Most of the pipework runs through the metal web joists.
The wiring mostly runs through the metal web floor joists. After the wiring was completed it was covered in 32mm split conduit using split T pieces where necessary. All the calculations for the wiring electrical load took into account that the wiring was in conduit and in insulation. This picture also shows the ventilation supply ducting passing through the upstairs floor for two of the bedrooms.
The waste from the first floor bathroom and ensuite is connected to a single stack which exits through the ground floor in the corner of the hall. The pipework has a rodding access point and it will be boxed in with a small hatch to the access point. This will then be inside a fitted cupboard.
These pictures show all the first fix installations. The electrical wiring is run through the metal web floor joists on one side of the house and the water pipes on the other. The left hand picture shows the extract ventilation pipe which connects to the ensuite in the foreground and the bathroom behind.

The exterior of the house has a plinth consisting of six courses of brick slips. The remainder of the house is clad with cedar tongue and groove which will be left untreated to weather to a silvery grey colour. This is part of our low maintenance design.

Calcium silicate board is screwed to the battens. A profiled steel mesh is then attached to the board.

The brick slips are glued to the board through the mesh with the brick slips spaced vertically by the profile shaped in the mesh.

The external wall insulation consists of 50mm thick high density Rockwall batts. These have been fitted to improve acoustic insulation. They were also fitted on the roof and hopefully they will help with decrement delay.

The batts are tightly fitted between 50mm square horizontal battens.

The batts are held in place by vertical counter battens which are covered with a membrane.

After many months of planning for the windows the original supplier went into receivership and we had to find a new supplier. The original windows were to be aluminium clad timber Gutmann design manufactured in UK under licence. While looking for replacements we found out about Rehau reinforced plastic profiles certified by PHI and were lucky to find a UK manufacturer, Solent Glazing, who were not too far from home. We visited their factory and were very pleased with the product and their service.

The separate aluminium sills are glued down.
The porch is finished.
The main bedroom door and sidelights are fitted.
Next to go in are the kitchen/diner french doors.
The front is finished.
The lift-slider doors work like a dream.
The largest triple glazed units in this frame were around 140kg each and took some lifting, but the effect is well worth all the work.
The balcony is bolted up.
It just needs the balcony glass panels to finish but it's not really the weather for using it yet.

Before the roofing can start the lead work around the two front dormers is completed. We didn't actually use lead but Lacomet FL.

We put 50mm high density Rockwool batts between the 100x50mm rafters.
The Nu-Lok roofing is delivered which consists of galvanised steel battens and porcelain tiles.
The side extension roof is completed and battening the main roof starts.
Well on the way now.
Ridge tiles go on.
Rear finished.

The frame is an unusual portal I-beam timber frame design which reduces thermal bridging to a minimum.
The sole plate was laid on 29/9/10 with the remainder of the frame being installed over the following two weeks.
This shows the construction of the individual frames.
The first floor decking was laid to make the frame installation easier.
A crane was needed to lift the remaining frames into position.
The 15mm OSB3 racking was nailed up covering all the openings which were to be opened up later.

Almost finished the racking.

The racking was covered with a Glidevale Protect TF200 membrane.

The front verandah and porch roof are added.

The rafters are fitted.

It's 29th November exactly two months after the sole plate was laid and now ready for the roof covering.

Digging out for the insulated raft foundation system went without any problems,
but little did we know what lay ahead!
We decided on using a PH certified foundation system which worked well with our type of wall construction.
The only one available at the time was the Isoquick system.
There is 250mm compacted type 1 sub-base with 50mm granite fines on top
That's a lot of insulation
In order to obtain the overall U factor required of 0.1W/m²K it uses 300mm of Peripor polystyrene base insulation and a 200mm thick upstand reducing to 100mm. It is a brilliant concept with all the insulation pieces locking together like a jigsaw puzzle. Ours was the first Isoquick system installed in UK.
A technician from Germany oversaw the fitting of the insulation which went smoothly.
Unfortunately the concrete laying did not go so well. A combination of cost cutting, by not using a pump, and the concrete setting too quickly left large voids in the 200mm slab which were detected using ultrasonic testing. The results were confirmed by drilling core samples.
The result of the farce was that the whole system was cut up using a diamond road cutter and taken away.
A lot of loads for the grab lorry
New polystyrene
Pumped concrete
At last
The second attempt went smoothly and we eventually got the foundation system we wanted.

The self-build house is a replacement for an old timber bungalow with the house being built in the garden of the bungalow which we are living in until we can move into the house. The bungalow will then be demolished.
Garden/building site to the right of the bungalow
Site clearance started in March 2010 with the removal of two garages, and levelling of the site.
A site hut is built
A new sewage treatment plant was installed which was a WPL Diamond DMS2. There was to be a deep bore soakaway from the DMS2 because there wasn’t sufficient space on the site for a conventional herringbone soakaway.
Drilling the borehole started in May 2010 after we had dug a 2.5m deep hole and put in five 1.2m diameter x 0.5m deep concrete rings. The borehole reached chalk after drilling down 47m. Unfortunately the chalk was water bearing so we couldn’t use the borehole as a soakaway but on the bright side we did have a well.
We had to think of an alternative and looked into using a reedbed system that would fit on site. Eventually we found details of the Klargester Reedbed System which fitted into the only available space on site and with which the Building Control Officer was happy.

We had wanted to build our own house for many years and then suddenly the opportunity presented itself. What sort of house should we build though? We wanted to reduce our household outgoings, so a house that used less energy and had low maintenance costs was needed. This was the start of a long process of research into low energy buildings.
We designed the house ourselves. The local planning department were not helpful and in total the detailed planning process took three attempts, but after taking all the various planning officers comments into account the final design was approved unanimously by the planning committee. The design had evolved and the look had changed considerably by the third design.
When it's built hopefully it will look something like this
and this.
During the research process decisions on whether to use a low or high thermal mass building were considered. We decided on relatively low thermal mass as this is England and when do we have long periods of hot weather! We considered different types of timber frame and in the end chose a portal timber I-beam frame design. This was when I found out about Passivhaus (PH). It was amazing, this was exactly the concept we were looking for.
We bought a copy of the Passivhaus Planning Package (PHPP) and after reading the manual a couple of times we started to enter data into the package. Although the software was quite complex, inputting correct data was essential to obtaining meaningful output. It took many months to finish getting everything spot on, but eventually the design met the PH criteria with a space heating requirement of 12kWh/(m²a) and a primary energy demand of 51kWh/(m²a).
We managed to source all the major building components which were certified by the Passivhaus Institute(PHI).
The type of insulation to be used was narrowed down to ‘Icynene LDR50’ or ‘Knauf Supafil Frame’. Icynene was decided upon because of its better airtightness qualities.
The concrete raft foundations are a German PH certified system called Isoquick which incorporates 300mm Peripor polystyrene insulation giving an overall U factor of 0.1 W/m²K.
The walls and roof are constructed using 350mm Steico I-beams sheathed with 15mm OSB3 giving racking strength. In addition to the 350mm internal Icynene there are 50mm high density Rockwool batts fitted to the outside of the OSB3. This gives an overall U factor of 0.09 W/m²K.
The roof covering uses the Nu-Lok system of black ceramic tiles and the walls are clad in untreated shiplap cedar.
The entrance doors are PH certified and manufactured by Internorm. The windows which are also PH certified are triple glazed and triple sealed and manufactured in the UK using Rehau Geneo profiles which are made of fibre reinforced plastic.
The high airtightness requirement of PH means there is a heat recovery and ventilation system. The compact unit we have decided upon is the Genvex Combi 185S. This incorporates an exhaust air heat pump to provide hot water and duct heating. A 2.8 kWp PV array will be installed on the South facing roof.
All interior and exterior lighting will be LED.
Aerating taps and showers will reduce water and energy use.
We used BuildDesk U to determine U factors and any potential interstitial condensation problems. WUFI will be used to accurately determine the need for an internal vapour membrane.
The local building control department were very interested in the design and have been very helpful.